Gas-vapor separating and gas purifying apparatus

ABSTRACT

Apparatus for separating vapor from pressurized gas and for then purifying the gas comprises a cylindrical pressure tank having a lower opening closed by a removable base member and having disposed within the tank a gas purifying element. An annular vapor separating chamber is formed in the base member and an annular passageway communicating therewith is formed between the outer wall of the purifying element and the inner wall of the tank. A formed tube connected to an inlet passageway in the base member directs a pressurized gas-vapor mixture tangentially into the annular chamber and in a plane generally at right angles to the axis thereof, thereby causing vortexing of the mixture around the chamber and upwardly, around the annular passageway between the purifying element and tank, to a gas permeable upper region of the purifying element. Vapor is centrifugally separated from the vortexing gas-vapor mixture, the condensate being gravity collected in the bottom of the annular chamber. The purifying element, which may contain several different purifying media, removes residual vapor and chemical and particulate impurities from the gas as the gas passes downwardly therethrough. Purified gas exits the tank through an outlet passageway in the base member. A drain valve, by which condensate is drained from the annular chamber, and a burst diaphragm, which prevents over-pressurization of the tank, are provided in the base member.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to the field of gas purifying apparatus and, moreparticularly, to combination gas-vapor separating and gas purifyingapparatus.

2. Description of the Prior Art

Compressed air (or gas) for self-contained respiratory air systems, suchas are commonly used by fire departments and scuba divers, and for othercritical applications, must be virtually free from vapor and fromparticulate and chemical contaminates. In addition to the moisture andcontaminants, such as dust and carbon monoxide or carbon dioxide,initially present in the air or gas before compression, otherimpurities, such as oil vapor from the compressor and particulate matterfrom the filter media, may be introduced by the compressing andpurifying operations. In many instances, when used for breathing, thepurified air or gas must meet stringent quality standards promulgated bythe Occupational Safety and Health Administration (OSHA) of the federalgovernment.

Purification is normally accomplished by first passing the compressedair or gas through vapor separators, for removal of water and oil vaporfrom the compressor, and then through filters which remove residualvapor and particulate and chemical contaminations. The filters used maybe simple, having only a dessicant for removal of moisture, or mayinclude such other materials as catalysts to convert carbon monoxideinto carbon dioxide and activated carbon (charcoal) to remove chemicalimpurities. Mechanical sieves may be provided for removal of particulateimpurities. Examples of filtering apparatus are disclosed by Robbins(U.S. Pat. Nos. 3,029,581 and 3,047,993), Jaubert (U.S. Pat. No.2,698,061), Squier (U.S. Pat. No. 2,728,407), Gibson, Jr. (U.S. Pat. No.3,008,540) and Sperlock (U.S. Pat. No. 3,127,257).

When, as is often the case, substantial quantities of vapor, includingwater and oil vapor, are present in the compressed gas or air, aseparate element for removing the vapor is normally provided to preventsaturation of the filter. Thus, two separate "filters" are normally usedin series, the first being a mechanical-type vapor separator to separateout most of the vapor and the second containing the filtering media toremove residual vapor and other impurities.

Jaubert discloses a single unit having a baffle-type moisture separatorand having a separate filter element for removing impurities in the gas,the incoming pressurized gas passing first through the baffles and thenthrough the purifying elements. However, the disclosed bafflearrangements are comparatively costly to fabricate and difficult toclean and are not particularly effective in vapor separation.

Heretofore, to the applicant's knowledge, there exists no simple,efficient and comparatively low-cost combination gas-vapor separatingand gas purifying apparatus.

SUMMARY OF THE INVENTION

A combination gas-vapor separating and gas purifying apparatus comprisesa pressure vessel having a vapor separating chamber formed in a baseportion thereof, and having disposed within portions of the vessel abovethe separating chamber a gas purifying means. A generally annularpassageway, formed between the outside of the purifying means and theinside of the vessel, communicates in a lower region with the separatingchamber and in an upper region with a gas permeable portion of thepurifying means. Vortexing means are provided for causing a mixture ofpressurized gas and vapor introduced into the vessel to vortex aroundthe separating chamber and upwardly around the annular passagewayadjacent the purifying means to cause centrifugal separation of vaporfrom the gas. Vapor condensing on the vessel and purifying means wallsis gravity-collected in the lower portion of the separating chamber.Means are provided for connecting a lower portion of the purifying meansto an outlet passageway to the vessel for flow of the purified gas fromthe vessel.

More particularly, the vessel comprises an elongate cylindrical tankclosed at the top and open at the bottom. A base member, threadablyreceived within the lower tank opening, is removable to allowreplacement of the purifying means. A cylindrical vapor separatingchamber is formed in an upper portion of the base member. The purifyingmeans comprises a cylindrical purifying element having a permeable upperportion and an open-ended projection at the bottom portion. A tubularconnecting element is disposed along the axis of the separating chamberand connects the purifying element projection with an outlet passagewayin the base member, thereby causing the separation chamber to be annularin configuration.

The vortexing means comprises a formed vortex tube having a verticalinlet portion received in the bottom of the separating chamber andconnected to an inlet passageway through the base member and having ahorizontal outlet portion directed tangentially along the outer wall ofthe separating chamber and in a plane generally at right angles to theaxis of the chamber.

A drain passageway, formed through the base member to communicate withthe lower portion of the separating chamber, enables condensed vapor tobe withdrawn therefrom by means of a drain valve. Over-pressureprotection is provided by a burst diaphragm which communicates with theinlet passageway of the base member through another passageway in suchmember.

Mechanical separation, by centrifuge action, of vapor present in apressurized gas is provided in the same tank in which subsequentpurification of the gas is accomplished by passing the gas downwardlythrough a purifying element. The purifying element may contain aplurality of purifying media such as silica gel for removal of residualvapor, a catalyst to convert carbon monoxide to carbon dioxide,activated carbon to remove chemical impurities, including carbondioxide, and a mechanical sieve to remove particulate impurities. Gaspurifying is thus made more simple and less costly than with heretoforeavailable purifying apparatus.

BRIEF DESCRIPTION OF THE DRAWINGS

A better understanding of the invention may be had from a considerationof the following detailed description, taken in conjunction with theaccompanying drawings, in which:

FIG. 1 is a vertical sectional view of the apparatus, showing the tank,purifying element and base;

FIG. 2 is a sectional view along line 2--2 of FIG. 1, showing the inlet,outlet, drain and pressure relief passageways through the base member;

FIG. 3 is a sectional view along line 3--3 of FIG. 1, showing theannular vapor separating chamber in the base member; and

FIG. 4 is a sectional view along line 4--4 of FIG. 1, showing theannular passageway between the purifying element and the inside of thetank.

DESCRIPTION OF THE PREFERRED EMBODIMENT

As best seen in FIG. 1, the gas-vapor separating and gas purifyingapparatus comprises generally a single pressure vessel or tank 10, abase member 12 threadably received in the open lower end of the tank anda gas purifying element or cartridge 14 disposed within the tank.

More specifically, the tank 10, formed in an elongate, cylindricalshape, has a conventionally domed, closed upper end 16 and an open lowerend which is internally threaded at an end portion 18. To enablewithstanding of pressures up to about 4500 psi, and to meet safetystandards requiring about a 4 to 1 safety factor while still remainingcomparatively lightweight, the tank 10 is preferably impact extrudedfrom a strong lighweight material such as type 6351-T6 aluminum alloy,which is hard annodized to inhibit corrosion. The tank may be about 16inches long and about 4.6 inches in diameter with a 0.70-inch wallthickness.

To close the open lower end of the tank 10, and to admit the purifyingelement 14, the base member 12 is formed to have an elongate upwardlyprojecting portion 20 which is externally threaded for screwing into thetank end portion 18. Below the portion 20, the base member 12 has aflanged lower portion 22 which has approximately the same outer diameteras the outside diameter of the tank 10. An inner portion of the basemember 12 is axially bored to form a cylindrical chamber 24 having anouter peripheral wall surface 26. The depth of the chamber 24 isapproximately equal to the length of the threaded portion 20, and may beabout 2.55 inches; the diameter of the chamber, which may be about 2.18inches, is smaller than the inner diameter of the tank 10 to provide astrong chamber wall 28. An annular groove 30 is formed around an upper,outer region of the portion 20 above the threads. To effect pressuresealing, upon assembly of the base portion 12 into the tank 10, anO-ring 31, having a backup ring 32, is installed in the groove.

An axial depression 34 is bored partially through the base member 12from the bottom of the chamber 24, and is internally threaded to receivea tubular filter connecting element 36, which is externally threaded ina lower region. When the connecting element 36 is installed in thedepression 34, an upper surface 38 of the element is at about the levelof an upper surface 40 of the base member wall 28. The connectingelement 36 causes the chamber 24 to be generally annular inconfiguration, and the chamber may be referred to as an annular, ratherthan a cylindrical chamber.

As also seen in FIG. 2, a radial outlet passageway 42 is formed througha side wall surface 44 of the base member lower portion 22. The innerend of the passageway 42 communicates with the bottom of the depression34 by means of a short vertical portion 46. An outer end portion 48 ofthe passageway 42 is threaded to receive a conventional threaded tubefitting 50. In an imposing relationship, an inlet passageway 56 isradially formed in the base member lower portion 22 and has a shortvertical portion 58 which communicates with a bottom surface 60 of thechamber 24. An outer portion 60 of the outlet passageway 56 is threadedto receive a conventional tube fitting 62.

Also formed in the lower portion 22 of the base member 12 is a pressurerelief passageway 64 (FIG. 2) which is angled from a pressure reliefport 66, spaced midway between the outer portions 48 and 60 of thepassageways 42 and 56, to communicate with an inner portion of the inletpassage 56. The port 66 is threaded to receive a pressure relief device68 which may be a burst disc or diaphragm having a burst pressuresomewhat above the intended operating pressure of the tank 10 and wellbelow the proof or burst pressure of the tank.

Opposite the port 66, and communicating radially through the base memberlower portion 22 is a threaded opening 70 for receiving a drain valve72. An inner end 74 of the opening 70 communicates with the bottomsurface 60 of the chamber 24 by means of a short vertical bore (notshown), Angled into an inner portion of the opening 70 is a drainpassageway 76 having an outer drain port 78 threaded to receive aconventional tube fitting 80.

A vortexing action of gas and vapor into the chamber 24, from the inletpassageway 56, is provided by a tubular vortexing element 84 which has alower vertical portion 86 threadably received within the upper portion58 of such inlet passageway (FIG. 1). A short upper, horizontal portion88 of the vortexing element 84 has an outlet opening 90 which issomewhat below the upper surface 40 of the base member 12, and which isdirected to emit gas and vapor tangentially along the chamber wallsurface 26 and in a plane generally perpendicular to the axis of thetank 10. Pressurized gas and vapor exiting through the outlet opening 90are thereby caused to vortex or swirl around the chamber 24 to separatevapor from the gas, as more particularly described below, before the gasenters the purifying element 14.

The purifying element 14 is formed with a rigid outer cylindricalsurface 92 having a somewhat smaller diameter than an inner diametersurface 94 of the tank 10, thereby forming, when the element isinstalled in the tank, an annular passageway 96 between the surfaces 94and 96 (FIGS. 1 and 3). A plurality of gas admitting perforations 98 areformed in a flat upper end surface 100 of the purifying element 14. Theupper surface 100 is maintained in spaced relationship with a concavetop inner surface 102 of the tank 10 by an annular spacer 104 having aplurality of radial openings or cutouts (not shown) to admit gas fromthe annular passageway 96 to an upper chamber 106 formed between suchsurfaces.

An open-ended elongate tubular portion 110 at the bottom of thepurifying element 14 projects axially downwardly and, when the purifyingelement is installed in the tank 10, extends into the connection element36, and may be sealed therein by an annular seal or O-ring 112. Aplurality of downwardly projecting edge portions 114, along the outeredge of a bottom 116 of the purifying element 14, supports the purifyingelement upon the base member upper surface 40. Such projections 114 arespaced apart to allow flow of gas therebetween from the chamber 24 intothe annular passageway 96.

Packed within the purifying element 14 may be a composite of variousfiltering or purifying media corresponding to the purifying function tobe performed. For example, a first or upper layer 126 may be formed ofactivated alumina to remove residual oil vapor from the gas. A nextlayer 122 may comprise silica gel to remove residual water vapor fromthe gas. Another layer 124 may comprise a catalyst, for example,Hopkolite, for converting carbon monoxide to carbon dioxide. Stillanother layer 126 may comprise activated carbon (charcoal) to removechemical impurities, including the carbon dioxide. At the bottom of thepurifying element, adjacent the projecting portion 110, a mechanicalfilter or sieve 128 may be positioned to remove particulate mattereither initially present in the gas or which may have been introducedduring the compression or purifying operations (for example, particlesof silica gel or activated carbon). The purifying element 14 may beprepacked with such various purifying media and may be completelydisposable, or it may be segmented in a manner (not shown) enablingdisassembly and recharging of the purifying media.

Operating of the apparatus is generally evident from the foregoingdescription. Pressurized gas, which may contain chemical and particulateimpurities as well as water and oil vapor, is directed into theapparatus through an inlet tube 130 which is connected to the fitting 60threaded into the inlet passageway 56. The unpurified gas-vapor mixtureis ejected through the opening 90 of the vortex element 84 and is causedto vortex or swirl around the annular chamber 24 and then vortexupwardly around the annular passageway 96. During such vortexing,substantially all of the water and oil vapor is centrifugally separatedfrom the gas and is condensed on the walls 26 and 94 and collected as aliquid 132 at the bottom of the chamber 24. The gas, now containing onlyresidual amounts of oil and water vapor, passes from the passageway 96through the annular spacer 104 into the upper chamber 106 and thencethrough the perforations 98 downwardly into the purifying element 14. Asthe gas is forced downwardly through the purifying element 14, theresidual vapor and the impurities in the gas are removed by thefiltering media 122-128 and the completely purified gas exits the filterthrough the open-ended projecting portion 110 and, via the connectingelement 36, outwardly through the outlet passageway 42 and to a tube 134connected to the tube fitting 50. From the tube 134 the purified gas maybe directed, for example, to a storage cylinder (not shown).

Periodically, the drain valve 72 is opened, either manually or otherwise(if it is a remotely actuated valve) and the liquid 132 is gravitydrained or forced by pressure in the tank 10 out through the passageway76 and through a tube 136 connected to the fitting 80 to a convenientreceptacle (not shown).

In the event pressure of the gas entering the base member 12, via theinlet passageway 56, exceeds the preselected burst pressure of the burstdisc 68, the disc ruptures and allows the gas to exit via the passage64, thereby preventing possible high pressure and dangerous rupturing ofthe apparatus. The burst disc 68 may be replaced by a pressure reliefvalve, not shown, or a pressure relief valve may be installed inaddition to the burst disc elsewhere on the apparatus. In the event thata pressure relieve valve is provided in addition to the burst disc 68,the relief pressure would preferably be set at a somewhat lower pressurethan the burst pressure of the burst disc.

Both gas-vapor separation, principally by mechanical means, andsubsequent gas purification is efficiently provided in a single unithaving a replaceable purifying element. By use of such apparatus,necessity for having a separate vapor removing unit is avoided andsystem complexity is reduced. If added filtering capacity is desired,several identical or similar units may be connected in series. When aplurality of the described apparatus is series connected, it isnecessary that all have burst disc 68 and drain valve 72. The relatedopenings 66, 70 and 78 may be plugged, or if desired different basemembers 12 may be provided for other than the first unit in the series.For example, a base member may be formed without the chamber 24 andvortexing element 84 and without described provisions for pressurerelief and draining. Use of such modified base members may reduceoverall systems costs; however, advantages associated with having agas-vapor separator and gas purifying element in the same unit willthereby be reduced.

Although there have been described hereinabove specific arrangements ofa gas-vapor separating and gas purifying apparatus in accordance withthe invention for the purpose of illustrating the manner in which theinvention may be used to advantage, it will be appreciated that theinvention is not limited thereto. Accordingly, any and allmodifications, variations or equivalent arrangements which may occur tothose skilled in the art should be considered to be within the scope ofthe invention as defined in the appended claims.

What is claimed is:
 1. A combination gas-vapor separating and gaspurifying apparatus, which comprises:a. a pressure vessel having aclosable opening, a base portion of said vessel having formed therein avapor separating chamber in communication with other portions of theinside of said vessel, said base portion also having formed thereininlet, outlet and drain passages,said inlet passage communicatingthrough said base portion with said separating chamber, said outletpassage communicating through said base portion with an inside portionof said vessel, said drain passage communicating through said baseportion with said separating chamber; b. purifying means adapted forpurifying a gas, said purifying means including a removable purifyingelement disposed within said vessel and installable through saidclosable opening,said purifying element having a gas permeable upperportion and an open lower portion, and being formed to provide agenerally annular passageway between outer portions thereof and adjacentinside portions of said vessel from said separating chamber to saidpermeable upper filter portion; c. means for connecting said lower openportion of said filter to said outlet passage; and d. vortexing meansfor causing a pressurized mixture of gas and vapor supplied to said baseinlet passage to vortex around said separating chamber and upwardlyaround and through said annular passageway to cause separation of saidvapor from said gas by centrifugal action, substantially vapor-free gasbeing passed to said permeable portion of said purifying element andliquefied, separated vapor being collected in said separating chamber.2. The invention as claimed in claim 1, wherein said purifying elementhas disposed therewithin a plurality of gas purifying media for causingremoval of residual vapor from said gas passed to said permeable portionand for removing from said gas particulate matter and preselectedgaseous impurities.
 3. The invention as claimed in claim 1, wherein saidvortexing means includes a tube having an inlet end portioncommunicating with said inlet passage and an outlet end portionpositioned relatively adjacent to the outer periphery of said separatingchamber and in a plane generally at right angles to the longitudinalaxis of said separating chamber.
 4. The invention as claimed in claim 1,wherein said vessel and said purifying element are generallycylindrical.
 5. The invention as claimed in claim 1, including a drainvalve connected to said drain passage.
 6. The invention as claimed inclaim 1, wherein said means for connecting said lower open portion ofsaid purifying element to said outlet passage comprises a tubularelement disposed along the axis of said separating chamber, whereby saidseparating chamber is caused to be annular in configuration.
 7. Theinvention as claimed in claim 1, including pressure limiting meanscommunicating through said base portion with said separating chamber,whereby to limit pressure in said vessel to below a predeterminedpressure level.
 8. The invention as claimed in claim 7, wherein saidpressure limiting means includes a pressure diaphragm having a burstpressure at said predetermined pressure level.
 9. The invention asclaimed in claim 1, wherein said closable opening is at the bottom ofsaid vessel and said base portion comprises a removable memberthreadably received in said closable opening.
 10. A gas-vapor and gaspurifying apparatus, which comprises:a. a cylindrical tank,said tankhaving a closed upper end and an open lower end portion, said lower endportion being internally threaded; b. a base member,said base memberhaving an externally threaded upper portion received by said internallythreaded lower end portion of said tank, said base member having axiallyformed in an upper portion thereof a cylindrical vapor separatingchamber, and having formed in lower regions thereof inlet, outlet anddrain passageways communicating with said chamber; c. purifying meansreplaceably disposed within said tank and adapted for purifying agas,said purifying means including a cartridge having disposed thereinpurifying media, said cartridge having a gas permeable upper end portionadapted for receiving a gas to be purified and a lower opening adaptedfor emitting a purified gas and being formed to provide, when disposedwithin said tank, an annular spacing between an outer wall thereof andan inner wall of said tank, and an upper chamber between said upper endportion thereof and an inner surface of said closed end of said tank,said annular spacing communicating at a lower region with saidseparating chamber and an upper with said upper chamber; d. means forconnecting said lower opening of said cartridge with said outletpassageway in said base member for a flow of purified gastherebetween,said means including a tubular member positioned to causesaid separating chambers to be generally annular in configuration; e.vortexing means adapted for causing a mixture of gas and vapor enteringsaid separating chamber from said inlet passageway to vortex around saidseparating chamber and around said annular spacing between saidcartridge and said tank, whereby to cause vapor separation from the gasvapor mixture by centrifugal action; and f. drain means adapted fordraining condensed vapor from said separating chamber.
 11. The inventionas claimed in claim 10, wherein said drain means includes a drain valveconnected to said base member and communicating therethrough to a lowerportion of said separating chamber, whereby condensed vapor may bedrained from said separating chamber.
 12. The invention as claimed inclaim 10, including pressure limiting means for preventing pressure insaid tank from exceeding a predetermined level.
 13. The invention asclaimed in claim 12, wherein said pressure limiting means includes adiaphragm adapted for bursting at about said predetermined pressurelevel.
 14. The invention as claimed in claim 13, wherein said diaphragmis connected to said base member and communicates therethrough with saidinlet passageway.
 15. The invention as claimed in claim 10, wherein saidvortexing means comprises a tube having an inlet portion connected tosaid base member and to said inlet passageway where said inletpassageway opens into said separating chamber, and having an outletportion directed along an outer wall of said separating chamber in anupper region thereof, said outlet portion being positioned in a planesubstantially at right angles to the axis of said chamber.
 16. Theinvention as claimed in said claim 10, wherein said cartridge includesmeans for refilling said cartridge, whereby exhausted purifying mediamay be replaced with fresh purifying media.
 17. The invention as claimedin claim 10, wherein said purifying means includes means for removingresidual vapor from said gas and includes means for removing particulatematter from said gas.
 18. The invention as claimed in claim 17, whereinsaid purifying media further includes means for converting carbonmonoxide impurities in said gas into carbon dioxide, and means forabsorbing said carbon dioxide.